Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
Grafx2 - GrafX2 is a bitmap paint program inspired by the Amiga programs Deluxe Paint and Brilliance.
Icon Editor by RedKetchup - View and edit Windows icons (ICO files) directly from the browser. Create icons in 8-bit, 24-bit, or 32-bit color depth. Extract all the layers of an ICO file as PNG images.
LibreSprite - Free and open source program to create animated sprites.
IconWorkshop - Application to create and manage software icons. A must for developers.